The present invention relates to a method of manufacturing a rotor for rotary fluid pumps, and more particularly to a method of making a hollow rotor provided with vane grooves to allow the smooth slide of vanes.
Recently, the rotary fluid pump for use in vehicles has been desired to be less in weight for saving energy. The pump can not reduce its weight without substituting the known solid rotor for a hollow rotor. The inventors of this application have proposed an easily producible rotor which is composed of a hollow rotor body, both side plates welded to the both sides of the body and either or both rotary shafts fixed to the side plates. The rotor has been disclosed under JP A No. 59-155592. However, the rotor has a problem that it is not always easy to finish the vane groove to the extent that the vane smoothly slides in the vane groove. The reason for this is that the vane groove is neither always made from a material suitable as a vane groove nor easy to be sufficiently finished because of being integrally made with the rotor body.
The present invention is intended to resolve the problem described above and provide a method to easily produce a rotor that is light in weight and provided with vane grooves sufficiently finished to allow the smooth slide of vanes.
In accordance with the present invention, a U-shaped vane-groove forming member is fabricated separately from a rotor body. The vane-groove forming member can be made from a suitable material and finished so as to allow the smooth slide of a vane. For example, a steel plate is easily U-shaped by press-working and finished by simple finishing steps to improve the sliding performance of a vane.
The hollow cylindrical body are formed with axially full-length slits by machining, while the both side plates are provided with radial slits. The axially full-length slits and the radial slits form a plurality of sockets each being adapted to receive a separately fabricated vane-groove forming member when the cylindrical body and the both side plates are assembled to a rotor body. The vane groove forming member is inserted into the socket and then joined with the rotor body by brazing. The slits may be provided after or before the cylindrical body and the both side plates are assembled. When the slit is formed after the assembling, the rotor body is made of a hollow cylindrical material such as a metal pipe and the like. When the slits are previously provided, the rotor body is made of a plurality of arcuate plates that is produced from the same hollow cylindrical material as when the slits are formed after the assembling.
The side plate and the rotary shaft can be fabricated separately from or integrally with each other. For example, the both are joined with each other by welding when separately fabricated. Otherwise, the both are molded as one body by casting or forging. The both side plates can be fabricated separately from or integrally with each other with the intervention of the rotary shaft.
The axially full-length slits in the cylindrical body as well as the radial slits in the both side plates are simple in shape and easy to be shaped by machining. The U-shaped vane-groove forming member is easily inserted into a socket defined by the slits both in the rotor body and the both side plates. The vane-groove forming member, after inserted in the slit, is fixed to the cylindrical body and the both side plates by brazing. It is easy to set a brazing material such as copper solder and the like in the slits in the side plate. For the purpose of easily setting the brazing material between the vane-groove forming member and the rotor body, the vane-groove forming member is arranged to have its upper edges slightly projected from the outer surface of the rotor body, the brazing material being disposed between the peripheral surface of the rotor body and the upper edges projected therefrom.
The advantages offered by the present invention are mainly that the vane-groove forming member is fabricated independently from the rotor body and made from a material suitable as a vane groove as well as by a method that is relatively simple and efficient as compared with the known method in which the vane groove is integrally formed in the rotor body, and that the vane groove is accurate and superior in sliding characteristics. The rotor body can be simple in shape and easy to be made because of being separated from the vane grooves. The rotor body is easy to join the side plates because of being simple in shape. The vane-groove forming member is easily manufactured by machining because of having a uniform U-shaped section. The separately fabricated vane-groove forming member is accurately fixed to the rotor body by a simple brazing method in which the vane-groove forming member is inserted in the slit of the rotor body in which brazing solders are previously disposed and then put in a furnace together with the rotor body. All in all, the present invention provides a simple method of manufacturing a hollow rotor superior in a vane-sliding performance.